The objectives of this research project are to examine the chemical correlates in the brain of various behavioral changes mediated or induced by neuroendocrinological alterations. The phenomena to be analyzed are the metabolic events occurring in the hypothalamus during sexual development and behavior; estrus, castration, androgensterilization; thermoregulation, hunger, thirst; and thyrotropin, adrenocorticotropin, and somatotropin regulation. These chemical studies will be an examination of the metabolic events associated with the behavioral-physiological changes; not the chemistry of the hormones or releasing factors. Chemical analyses will be made of specific nuclei of the hypothalamus controlling these behavioral- physiological interactions and of the extrahypothalamic structures modulating these interactions, e.g., the limbic system. To determine the exact specificity of these chemical events, nuclei from other areas of the hypothalamus not involved in control of these functions and other areas of the brain, e.g., cortex, cerebellum will also be analyzed. The methodology used is that of quantitative histochemistry supplemented by immunochemical methods. These methods involve the dissection of discrete, histologically defined nuclei from freeze-dried, unfixed, unstained tissue sections. Samples weighing 0.5 micro gram or less are to be quantitatively analyzed for the following: enzymes reflecting the overall activity through a metabolic pathway, enzymes which are control points in a pathway, enzymes in pathways unique to brain, lysosomal enzymes, biogenic amines and enzymes associated with their metabolism, brain specific proteins, and neuronal nucleic acids.